Feed Calculator for Machining

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Feed mm/min

Type a value as mentioned and get the feed mm/min

Spindle RPM

Feed/Tooth

No. of Cutting Edges

Feed Per Minute:

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Feed (f)

• l (mm/min): Machined length per minute
• n (min^-1): Spindle speed

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This formula is used to calculate the feed rate per revolution from the spindle speed and the length cut per minute.
Example:
Machined length per minute (l) = 150 mm/min
Spindle speed (n) = 600 min^-1
In this case, the feed rate per revolution (f) is 0.25 mm/rev.

Cutting Speed (vc)

• π (3.14): Circular constant
• Dm (mm): Diameter of workpiece
• n (min^-1): Spindle speed

This formula is used to calculate the cutting speed from the spindle speed and the diameter of the workpiece.
Example:
Diameter (Dm) = 60 mm
Spindle speed (n) = 500 min^-1
In this case, the cutting speed (vc) is approximately 94 m/min.

Machining Time (Tc)

• lm (mm): Length of workpiece
• l (mm/min): Machined length per minute

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This formula is used to calculate the machining time from the length of the workpiece and the spindle speed.
Example:
Feed (f) = 0.2 mm/rev
Spindle speed (n) = 1100 min^-1
Length of workpiece (lm) = 120 mm
First, the machined length per minute is calculated, in this case from the rotational speed and the feed amount.
Machined length per minute (l) = n × f
= 0.2 × 1100 = 220 mm/min
Substitute this into the formula:
Tc = lm ÷ l
= 120 ÷ 220
= 0.55 (min) × 60
= 33 (sec)
The machining time (Tc) is approximately 33 seconds.

Theoretical Finished Surface Roughness (h)

• f (mm/rev): Feed per revolution
• Re (mm): Insert’s corner radius

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This formula is used to calculate the theoretical finished surface roughness from the blade corner radius of the insert and the feed per revolution.
Example:
Feed per revolution (f) = 0.1 mm/rev
Insert’s blade corner radius (Re) = 0.5 mm
In this case, the theoretical finished surface roughness (h) is 2.5 µm.

Net Power (Pc)

• ap (mm): Depth of cut
• f (mm/rev): Feed per revolution
• vc (m/min): Cutting speed
• Kc (MPa): Specific cutting force
• η: Machine efficiency

This formula is used to calculate the net power from the depth of cut, the feed per revolution, the cutting speed, the specific cutting force, and the machine efficiency.
Example:
Depth of cut (mild steel: ap) = 5 mm
Feed per revolution (f) = 0.1 mm/rev
Cutting speed (vc) = 140 m/min
Machine efficiency (η) = 80% (0.8)
Given:
Specific cutting force (Kc) = 3610 MPa
In this case, the net power for machining (Pc) is 5.26 kW.

Kc Values (Cutting)

Workpiece material	Tensile strength (MPa) and stiffness	Specific cutting force Kc (MPa) for each feed
		0.1 (mm/rev)	0.2 (mm/rev)	0.3 (mm/rev)	0.4 (mm/rev)	0.6 (mm/rev)
	Mild steel (SS400, S10C, etc.)	520	3610	3100	2720	2500	2280
	Medium steel (S45C, S50C, etc.)	620	3080	2700	2570	2450	2300
	Hard steel (S55C, S58C, etc.)	720	4050	3600	3250	2950	2640
	Tool steel (Carbon tool steel (SK), etc.)	670	3040	2800	2630	2500	2400
Tool steel (Alloy tool steel (SKS), etc.)	770	3150	2850	2620	2450	2340
Chrome-manganese steel (Manganese carbide (MnC), etc.)	770	3830	3250	2900	2650	2400
Chrome-manganese steel (Manganese carbide (MnC), etc.)	630	4510	3900	3240	2900	2630
Chrome molybdenum steel (SCM grades, etc.)	730	4500	3900	3400	3150	2850
Chrome molybdenum steel (SCM grades, etc.)	600	3610	3200	2880	2700	2500
Nickel chrome molybdenum steel (SNCM415, etc.)	900	3070	2650	2350	2200	1980
Nickel chrome molybdenum steel (SNCM439, etc.)	352HB	3310	2900	2580	2400	2200
Hard cast iron	46HRC	3190	2800	2600	2450	2270
Meehanite cast iron (FC350, etc.)	360	2300	1930	1730	1600	1450
Gray cast iron (FC250, etc.)	200HB	2110	1800	1600	1400	1330

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